To study the association between several exposures of interest and the occurrence of infectious loco-regional complications of pharyngitis in children.

Investigators will include in the study (after agreement of child and parents):

• Cases: children < 18 years old hospitalized for peripharyngeal suppurations, diffuse cervical cellulitis or cervical adenophlegmon in participating Ear, Nose & Throat (ENT) and pediatric departments.
• Controls: children < 18 years old with pharyngitis but without infectious complications recruited by general practitioners (GPs) or by primary care pediatricians in private setting, matched to cases by age, date of infectious complication (index date), delay between the pharyngitis and the index date and, if possible, the referring physician.

Primary endpoint: Difference in the frequency of exposure to various factors among cases and controls during an exposure window going from the date of diagnosis of pharyngitis to day -0.5 of the index date of the complication.

Several exposure of interest will be compared between cases and controls. One specific main exposure of interest during a predefined window of exposure has been defined but will not be revealed to investigators to avoid selection bias. Several secondary exposure of interest were a priori defined but will not be revealed to investigators to avoid selection bias.

Inclusion Criteria:

Cases: children < 18 years old hospitalized for peripharyngeal suppurations, diffuse cervical cellulitis or cervical adenophlegmon in participating Ear, Nose & Throat (ENT) and pediatric departments.

Controls: children < 18 years old with pharyngitis but without infectious complications recruited by general practitioners (GPs) or by primary care pediatricians in private setting, matched to cases by age, date of infectious complication (index date), delay between the pharyngitis and the index date and, if possible, the referring physician.

Exclusion Criteria:

Children (cases or controls) with chronic renal failure, hemophilia, chronic thrombocytopenia or immunosuppression (constitutional or iatrogenic) at the time of pharyngitis

Cases: participating Ear, Nose & Throat (ENT) and pediatric departments Controls: recruited ''in office settings'' by general practitioners (GPs) or by primary care paediatricians